UNIVERSITY   OF   CALIFORNIA 

COLLEGE    OF   AGRICULTURE 

AGRICULTURAL   EXPERIMENT  STATION 

CIRCULAR  No.  256 
January,  1923 

THE  CONTROL  OF  WILD  MORNING  GLORY 

By  CLYDE  C.  BAENUM 


;. 

* 

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Typical  Morning  Glory  Vine. 


CONTENTS 

PAGE 

Introduction    2 

Distribution  of  Morning  Glory ■ 5 

Plant  Physiology  in  Relation  to  Control 6 

"Cutting''  as  a  Means  of  Control 8 

Alfalfa  as  a  Smother  Crop 12 

Smothering  with  Non-living  Material 13 

Pasturing  with  Hogs  and  Sheep 14 

Salt  Brine  -  . * : 14 

Sodium  Arsenite  - 15 

Commercial  Weed  Killers 17 

Carbon  Bisulfid  for  Small  Patches 18 

Prevention  19 

Summary    21 

Bibliography   22 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


DIRECTOR'S    NOTE 

This  circular  has  been  prepared  in  response  to  numerous  inquiries 
received  by  the  Agricultural  Experiment  Station  and  the  State  De- 
partment of  Agriculture  at  Sacramento  regarding  Morning  Glory 
control.  The  recommendations  are  not  very  encouraging  but  are  the 
best  that  can  be  made  at  present.  The  clean  culture  method  described, 
although  expensive,  is  ultimately  effective  and  has  proved  economical. 
The  use  of  sprays  for  weed  control  in  the  fog  belt  requires  for  suc- 
cessful results  the  services  of  a  well-informed  worker. 


INTRODUCTION 

The  term  "Morning  Glory"  is  applied  to  a  certain  weed  found 
throughout  the  cultivated  lands  of  almost  every  rural  community  in 
the  state  of  California.  It  forms  twining  green  mats  and  owes  its 
common  name  to  its  white  flowers  which  open  early  in  the  morning. 
(See  frontispiece.)  Different  names  are  applied  in  various  places  to 
this  weed,  such  as  Orchard  Morning  Glory,  Field  Morning  Glory, 
Field  Bindweed,  European  Bindweed,  and  Cornbind.  All  these 
names  apply  to  a  single  species,  an  introduced  weed,  which  came  to 
America  from  Europe  and  spread  from  the  Atlantic  seaboard  to  the 
Pacific  Coast.  The  botanical  name  of  the  plant  is  Convolvulus 
arvensis. 

Wild  morning  glory  is  a  perennial;  that  is,  it  lives  through  the 
year,  and  is  annually  renewed  by  means  of  a  very  extensive  root 
system  of  succulent  underground  stems  and  fibrous  roots,  which  may 
penetrate  to  depths  of  six  to  ten  or  more  feet  according  to  the  soil 
formation.  (See  fig.  1.)  It  usually  gains  a  start  in  cultivated  fields 
from  seeds  sown  in  carelessly  screened  seed  grain  or  scattered  in 
fresh  barnyard  manure  which  had  not  been  composted  enough  to  heat, 
germinate,  and  kill  them.  Bean  or  grain,  straw  used  as  mulch  also 
often  carries  the  seed.  Small  patches  of  morning  glory  often  arise 
from  seedlings  or  small  fragments  of  roots.  These  should  be 
eradicated  and  they  can  be  if  care  is  taken  to  dig  them  out  thoroughly 
during  the  first  year.  Morning  glory  seed  is  described11  as  follows: 
"A  dark  brown  oval  seed  with  a  convex  face,  the  opposite  side  ridged 
with  a  broad  ridge.  Seeds  measure  approximately  one-sixth  of  an 
inch  in  length,  the  surface  is  roughened  and  somewhat  dull."     (See 


Circular  256] 


THE  CONTROL  OF  WILD   MORNING   GLORY 


fig.  2.)  The  plant  often  increases  the  area  covered  by  sending  out 
lateral  roots  from  its  main  root  which  in  turn  send  up  sprouts  to  the 
surface  and  more  roots  leading  down  to  moisture  and  food  supplies 
underground.      (See  fig.  3.)     The  plants  thus  grow  in  an  annually 


Fig.   1. — Vines  and  part  of  root  of  wild  morning  glory  showing  great  depth  of 

penetration  of  roots. 


increasing  circle.  At  the  same  time,  in  the  regular  course  of  plowing 
and  cultivation  many  of  the  lateral  roots  are  torn  loose  and  carried 
long  distances.  In  every  case  where  these  root-branches  are  embedded 
in  the  moist  soil  under  favorable  conditions,  they  establish  themselves 
and  form  other  colonies,  where  the  process  is  repeated. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Fig.  2. — Leaves,  flower  buds,  open  flowers,  mature  seed  capsules  and  seeds  of 
wild  morning  glory  (natural  size).  Insert:  wild  morning  glory  seeds  magnified 
five  times. 


Circular  256] 


THE   CONTROL   OF  WILD   MORNING   GLORY 


DISTRIBUTION 

Morning  glory  is  the  most  serious  weed  pest  in  the  state  of  Cali- 
fornia today  and  is  found,  according  to  a  survey  made  by  the  United 
States  Department  of  Agriculture  in  1921  through  the  cooperation 
of  the  farm  advisors,  in  the  following  counties:  Humboldt,  Mendo- 
cino, Sonoma,  Marin,  Napa,  Solano,  Yolo,  Sutter,  Butte,  Tehama, 
Shasta,  Yuba,  Placer,  Sacramento,  Contra  Costa,  Alameda,  San 
Joaquin,   Stanislaus,   Merced,   Madera,   Santa   Cruz,   Monterey,   San 


M>V 


%i„K 


¥  l£k  i    i  ■  ■■■        W'  r* 


Fig.  3. — Morning  glory  plant  showing  part  of  root  system  and  method  of  spreading 

by  underground  branches. 


Luis  Obispo,  Santa  Barbara,  Ventura,  Los  Angeles,  Orange,  San 
Bernardino,  Riverside,  and  San  Diego.  The  weed  is  found  in  many 
other  counties  as  well  where,  however,  it  is  of  less  economic  impor- 
tance. This  widespread  distribution,  following  the  path  of  extensive 
agricultural  development  in  the  richest  soils  of  the  state,  shows  very 
plainly  the  serious  menace  of  this  weed  to  our  agriculture.  (See  figs. 
4  and  5.)  In  California  thousands  of  acres  of  otherwise  fertile  soil 
are  abandoned  to  morning  glory,  and  throughout  the  United  States 
many  times  as  many  acres  yield  little  or  no  crops  because  of  it.  It 
is  the  duty  of  every  agriculturist  to  help  check  this  menace  to  agri- 
culture.    This  weed  can  be  controlled  under  certain  conditions;  it 


b  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

therefore  seems  advisable  to  publish  this  circular  to  explain  the  best 
known  methods  of  attacking  the  problem  of  control.  They  are 
methods  recommended  by  investigators  in  all  parts  of  the  world,  and 
some  of  them  may  be  applicable  to  conditions  in  California. 


PLANT    PHYSIOLOGY    IN    RELATION    TO    CONTROL 

The  farmer  who  would  try  to  rid  his  land  of  morning  glory 
should  bear  in  mind  a  few  helpful  facts  regarding  plant  nutrition 
and  physiology.  Plants  manufacture,  by  means  of  sunlight  and  the 
green  coloring  matter  (chlorophyll)  in  their  leaves  and  stems,  simple 


Wm%*&& 


Fig.  4. — Tomato  field  badly  infested  with  wild  morning  glory. 


sugars  which  are  soon  changed  to  starch  by  chemical  action  and 
stored  in  the  leaves  during  the  day.  (In  this  manufacturing  process 
the  plant  absorbs  carbon  dioxide  gas  from  the  atmosphere,  and  by 
some  chemical  change,  little  understood,  combines  this  gas  with  water 
in  the  living  cells  to  form  these  simple  sugars.  Sugars  are  soluble 
and  can  be  transported  in  a  liquid  form  through  the  plant  system 
from  cell  to  cell,  while  starch,  as  such,  is  insoluble  and  cannot  be 
thus  transported.)  During  the  hours  of  darkness  the  insoluble  starch 
manufactured  during  the  previous  day  is  changed  back  to  sugar  and 
carried  down  to  the  roots  where  it  is  utilized  for  new  root  growth  and 
cell  structure,  or  again  changed  and  stored  as  starch.  It  is  by  this 
process  that  the  plant  grows,  with  the  support  of  a  good  root  system 


Circular  256] 


THE   CONTROL   OF  WILD   MORNING   GLORY 


and  good  soil,  if  a  water  supply  be  available.  Any  mechanical  or 
chemical  interference  with  any  one  portion  of  the  plant  tends  to 
decrease  its  vitality.  As  the  season  advances,  the  morning  glory 
plants  continue  to  send  the  elaborated  plant  foods  or  sugars  to  be 
transformed  and  stored  in  their  roots,  and  these  roots  gradually 
become  richly  charged  with  starch.  Although  frosts  come  and  kill 
the  tops,  the  roots  remain  alive  throughout  the  winter,  and  await  only 
the  coming  of  warm  weather  for  renewing  their  activity. 


Fig.  5. — Small  areas  of  morning  glory  such  as  this  should  be  kept  below  ground. 
Seeds  from  this  colony  are  easily  spread  to  the  clean  soil. 


Spring  weather  brings  up  new  shoots  which  grow  rapidly  by  using 
the  large  quantities  of  stored  plant  food  remaining  in  the  roots  from 
the  past  summer.  The  amount  of  this  stored  food  is  so  large  that 
cutting  the  tops  off  from  time  to  time  has  little  effect  on  the  plant, 
which  sprouts  repeatedly  after  successive  cuttings  with  apparently 
undiminished  vigor,  especially  if  it  has  made  any  considerable  growth 
of  leaves  in  the  intervals  between  cuttings.  During  these  intervals 
the  plant  restores  the  starch  content  in  a  very  few  days.  Any  method 
which  tends  to  deplete  the  stored  up  food  supplies,  without  per- 
mitting the  plants  to  recuperate,  hastens  the  end  of  the  plant's 
growth. 

These  facts  will  aid  the  farmer  to  choose  the  method  of  eradication 
best  suited  to  his  case. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


"CUTTING"    AS    A    MEANS    OF    CONTROL 

The  method  of  control  that  is  recommended  by  nearly  all  investi- 
gators is  that  of  systematic,  thorough  "cultivation,"  by  which  they 
mean  the  cutting  of  the  plants  below  the  surface  of  the  soil  with 
horizontal  blades.  (See  fig.  6.)  This  method  is  here  referred  to  as 
1 '  cutting. ' '  All  the  investigations  have  proved  its  efficacy  and  estab- 
lished the  fact  that  proper  procedure  along  these  lines  will  eradicate 


Fig.  6. — One-horse  weed  knife,  made  by  blacksmith,  used  in  tomato  culture. 

the  pest.     Adequate  implements  can  be  purchased  or  made  in  local 
blacksmith  shops.     (See  figs.  7  and  8.) 

Frederic  T.  Bioletti  carried  on  extensive  investigations  at  the 
University  Farm  at  Davis  in  the  summer  of  1910  and  reported  his 
findings  in  a  circular  issued  by  this  Station  now  out  of  print.4  He 
found  that  ordinary  orchard  cultivation  was  not  sufficient  to  control 
the  weed.  He  further  showed  that,  if  a  field  of  ten  acres  was  thoroughly 
covered  every  five  days  during  the  growing  season  by  a  weed  knife, 
4!/2  feet  long  and  4  inches  wide,  drawn  by  a  team,  practically  no  living 
plants  would  be  left  in  the  field  to  reappear  the  following  year.  (See 
fig.  7.)     The  morning  glory  was  not  allowed  to  appear  above  the 


Circular  256] 


THE   CONTROL   OF  WILD   MORNING   GLORY 


surface  at  any  time  during  the  course  of  the  experiment.  In  this 
way  he  succeeded  in  killing  99.95  per  cent  of  all  the  morning  glory 
in  the  first  three  feet  of  soil.  This  work  was  done  on  a  good  type 
of  deep  soil  where  the  weed  flourished  in  spite  of  ordinary  culture. 
The  field  is  now  planted  in  grapes  and  is  easily  kept  clean  of  weed 
growth.  The  results  were  not  so  successful  when  the  interval  between 
the  cuttings  was  seven  days. 


Fig.   7. — Two-horse  weeder  used   for  morning   glory   control. 

raised  from  the  seat. 


The  blade  can  be 


Investigations  of  clean  culture  methods  carried  on  by  the  Spreckels 
Sugar  Company1  at  Spreckels  and  elsewhere  indicate  that  this  method 
of  control  is  satisfactory  when  the  cuttings  are  frequent  enough 
to  prevent  the  appearance  of  green  leaves.  It  was  found  that  the 
interval  of  five  days  between  cuttings  was  the  longest  that  could  be 
allowed. 

During  the  year  1915-16  some  work  was  done  at  Davis  by  Thomas 
Tavernetti  on  the  control  of  the  morning  glory  by  cultural  means,  in 
conjunction  with  the  work  done  by  George  P.  Gray  in  the  study  of 
chemical  methods  of  control.  Tavernetti  found  that  the  method  of 
plowing  by  which  the  field  was  plowed  to  a  depth  of  eight  inches 


10  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

every  two  weeks  during  the  period  beginning  February  15,  1915,  and 
closing  October  27,  1916,  was  expensive  and  unsatisfactory.  It  was 
difficult  to  keep  the  plowshares  sharpened  and  consequently  many 
roots  were  not  cut.  The  intervals  between  the  plowings  were  too 
long,  and  green  plants  appeared  from  time  to  time.  As  a  result  the 
plants  recuperated  many  times  during  the  summer  and  were  not 
seriously  weakened.  The  rough  plowed  land  dried  out  rapidly  and 
the  roots  used  little  of  their  reserves.  Plants  in  well  cultivated  soil 
where  a  weeder  was  run  every  five  days  during  the  growing  season 


££Mm 


Fig.  8. — Three-horse  weeder,  made  by  blacksmith,  used  for  morning  glory  control. 
For  heavy  soils  a  shank  should  be  placed  at  center. 

used  their  reserves  much  more.  The  Alameda  Sugar  Company  at 
Alvarado,  Alameda  County,  California,  has  imported  a  cutting 
machine  which  cuts  the  morning  glory  roots  eighteen  inches  below 
the  surface  of  the  soil,  thereby  enabling  the  growers  to  develop  a 
crop  of  beets  before  the  morning  glory  recovers  sufficiently  to  injure 
them.     (See  fig.  9.) 

The  work  done  at  Davis  on  weed-cutting  makes  possible  the  follow- 
ing recommendations : 

1.  " Cutting"  should  be  more  frequent  in  the  spring  and  early 

summer  than  in  the  late  summer  and  fall. 

2.  The  land  should  not  be  allowed  to  dry  out  during  the  summer. 

3.  The  "cutting"  should  be  deep.     (See  fig.  10.) 

After   studying  the  work  of  the   investigators,   it   appears  that 
eradication  by  clean  culture  can  best  be  done  as  follows : 


Circular  256] 


THE   CONTROL  OF  WILD   MORNING   GLORY 


11 


1.  Plow  deep    (8  to  10   inches)    early  in  the  season  before  the 

spring  growth  of  morning  glory  has  appeared.  Work  the 
soil  into  as  good  condition  as  possible.  Do  not  work  the 
soil  when  wet. 

2.  Provide  a  substantial  weecler — horse  or  tractor  drawn,  accord- 

ind  to  the  size  of  the  infested  area  and  farm  conditions — 
and  use  it  every  five  days  after  the  first  morning  glory 
sprouts  appear. 


Fig.  9. — A  very  efficient  type  of  weecler  and  sub-soiler,  drawn  by  80  h.p.  Holt 
tractor  and  running  16  to  18  inches  deep.  With  this  machine  it  is  possible  to 
grow  sugar  beets  without  hindrance  from  morning  glory.  The  implement  is  made 
at  Liverpool,  England. 

3.  Run  the  weeder  as  deep  as  it  can  be  drawn  (4  to  6  inches  at 

least)  ;  since,  the  deeper  the  cutting,  the  less  likelihood  is 
there  that  the  plants  will  reach  the  light  before  the  next 
cutting. 

4.  After  irrigation,  cultivate  as  soon  as  the  soil  is  dry  enough  in 

order  to  prevent  the  appearance  of  green  leaves. 

5.  Do  not  allow  the  plants  to  reach  the  surface  at  any  time  during 

the  summer.  Unless  the  work  is  done  thoroughly  it  is 
toasted. 

The  clean  culture  method  is  dependent  on  non-recuperation  of  the 
plant.  Gradual  depletion  of  the  food  stored  in  the  root  systems  is 
therefore  brought   about  by  the  continued  removal  of   all  sprouts, 


12 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


since  these  draw  on  this  stored  up  food  as  long  as  they  are  below 
ground.  Continual  cultivation  will  tend  to  maintain  moisture  in  the 
soil,  thus  encouraging  plant  growth  and  forcing  depletion  of  the 
stored  up  food  in  the  roots.  The  frequent  use  of  a  weeder  will  form 
a  hard  plow  sole  below  the  surface  mulch.  This  sole  should  be  broken 
up  before  the  heavy  rains  come  in  order  to  permit  the  water  to  pene- 
trate. A  little  care  taken  the  following  summer  to  dig  out  any  stray 
plants  of  morning  glory  will  remove  all  traces  of  the  pest. 


Fig.  10. — The  Alameda  Sugar  Company  at  Alvarado,  California,  use  this 
weeder,  drawn  by  80  h.p.  Holt  tractor,  in  preparation  of  morning  glory  infested 
beet  land.     It  runs  10  to  12  inches  deep. 


ALFALFA  AS   A   SMOTHER   CROP 

The  term  " Smother  Crop"  is  used  to  denote  luxuriant  crops 
which  grow  rapidly  and  densely  enough  to  completely  shade,  and 
partly  exclude  fresh  air  from,  certain  undesirable  plants  which  may 
be  growing  on  the  same  soil.  The  dense  shade  falling  on  the  more 
slowly  growing  weeds  prevents  their  manufacturing  sugars  and  thus 
hinders  their  growth.  Such  crops  as  cowpeas,  Rhodes  grass,  sweet 
clover,  vetches,  and  alfalfa  may  be  classed  as  smother  crops.  Alfalfa 
is  the  very  best  all  round  smother  crop  in  California,  though  other 
plants  can  be  successfully  used  on  certain  soils  to  control  minor  weeds. 

For  the  general  farmer,  growing  field  crops  such  as  grain,  potatoes, 
and  corn,  one  of  the  best  methods  of  ridding  fields  of  morning  glory 
is  smothering  with  alfalfa,  provided  irrigation  is  available.  If  the 
morning  glory  is  vigorous  and  has  practically  over-run  the  field,  that 
is  good  evidence  of  the  fertility  of  the  soil  and  its  probable  suitability 
for  alfalfa.     It  must  be  understood  that  if  the  alfalfa  is  to  choke 


Circular  256]  THE  CONTROL  OF  WILD   MORNING   GLORY  13 

out  or  smother  the  weeds,  the  soil  and  moisture  conditions  must  be 
such  as  to  insure  a  fine,  even  stand  of  alfalfa  within  a  short  time 
after  seeding  and  before  growth  of  morning  glory  begins  in  the 
spring.  The  soil  should  be  well  prepared  by  deep  plowing  as  early 
in  the  fall  as  possible;  first,  in  order  that  the  morning  glory  shall 
not  go  to  seed;  second,  in  order  to  insure  a  good  seed  bed  and  a 
greater  penetration  of  rainfall;  third,  in  order  to  be  able  to  sow 
the  alfalfa  early,  so  that  it  may  start  before  the  morning  glory 
roots,  in  the  colder  soil  below,  have  sent  up  their  new  shoots.  The 
deeper  the  plowing  and  the  more  thorough  the  work,  the  later  the 
morning  glory  will  come  through.  Deep  cultivation  before  seeding 
will  pull  out  and  destroy  most  of  the  loosened  roots.  Sow  the  alfalfa 
seed  shallow,  eighteen  pounds  to  the  acre,  with  a  drill,  in  February 
if  possible.  In  those  parts  of  California  where  temperatures  do  not 
go  below  25°  F.,  February  is  none  too  early.  Seed  sown  then  gives 
the  best  results.  The  maintenance  of  alfalfa  on  a  field  for  two  to 
three  years  often  so  weakens  the  morning  glory  that  after  a  deep 
plowing,  followed  by  a  year  of  intensive  cultivation,  the  weed  is 
controlled.  The  Spreckels  Sugar  Company1  found  that  the  use  of 
alfalfa  was  the  best,  most  economical,  and  at  the  same  time  most 
profitable  method  of  control  where  the  soil  was  suitable  for  this  crop. 
The  method  did  not  prove  completely  effective,  as  there  was  some 
morning  glory  on  the  land  even  after  three  years  of  alfalfa  planting. 
But  this  was  largely  on  account  of  the  poor  stand  obtained  and  the 
slow  rate  of  growth  of  alfalfa  under  the  climatic  conditions  of  the 
region. 

SMOTHERING    WITH    NON-LIVING    MATERIAL 

In  attempts  to  eradicate  morning  glory  by  smothering  with 
organic  matter,  such  material  as  eucalyptus  leaves,  beet  pulp,  manure, 
straw  and  tar  paper  have  been  tried  and  proved  inadequate. 

The  Spreckels  Sugar  Company1  have  carried  on  extensive  experi- 
ments in  this  line  also.  Tar  paper  was  laid  over  morning  glory 
patches,  lapped  four  inches,  and  the  laps  covered  with  dirt.  The 
plants  had  pushed  through  the  laps  by  May  and  grew  vigorously. 
Eucalyptus  leaves  piled  on  the  soil  six  inches  deep  over  morning 
glory  were  of  no  avail.  Beet  pulp  piled  on  the  ground  fifteen  inches 
deep  was  no  better.  When  barnyard  manure  was  piled  on  the  weeds 
to  a  depth  of  six  feet,  the  plants  and  flowers  soon  appeared  on  top 
of  the  heap.     Straw  has  also  proved  inadequate. 


14  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


PASTURING    WITH    HOGS    AND    SHEEP 

Cox2  in  his  bulletin  on  morning  glory  states  that  the  roots  taste 
like  sweet  potato  (both  plants  belong  to  the  same  family,  Convolvu- 
laceae).  There  are  two  methods  of  pasturing  fields  badly  infested 
with  morning  glory  outlined  by  Cox.2  One  of  these  is  to  turn  hogs 
into  the  field  immediately  after  the  crop  is  harvested  and  to  allow 
them  to  root  as  best  they  may.  They  will  eat  some  of  the  tops  and 
dig  out  the  more  easily  reached  roots  until  in  the  course  of  three 
years  or  less  the  field  may  become  a  profitable  crop-producing  area 
again.  Under  the  second  plan  the  field  should  be  first  deeply  plowed, 
preferably  in  the  early  spring.  At  frequent  intervals  during  the 
summer,  when  convenient,  the  field  should  be  replowed,  exposing  the 
roots  so  that  the  hogs  may  more  easily  reach  them. 

Cox2  states  that  by  this  method  the  weed  may  be  controlled  in 
one  year,  unless  the  underground  parts  extend  too  deep  to  be  reached 
by  the  hogs.  As  in  California  the  roots  always  extend  several  feet 
below  the  surface,  there  is  little  hope  of  controlling  the  pest  in  this 
state  by  this  means. 

SALT   BRINE    METHOD 

It  has  been  a  matter  of  common  knowledge  for  many  years  that 
plants  cannot  endure  large  quantities  of  ordinary  salt.  If  used  in 
sufficient  quantities  it  will  kill  morning  glory  plants.  Salt  in  small 
amounts  is  not  poisonous  to  man  or  animals;  the  material  is  easy  to 
apply,  easy  to  obtain,  and  is  relatively  cheap.  On  the  other  hand  the 
use  of  salt  on  land  prevents  the  growth  of  all  vegetation  for  a  number 
of  years,  varying  according  to  the  amount  applied  and  the  amount 
of  leaching  by  rains  or  irrigation  and  the  consequent  drainage.  If 
applied  on  large  fields  in  large  quantities  the  farmer  will  have  to 
contend  with  an  ' '  alkali ' '  problem  instead  of  with  the  morning  glory. 
In  the  eastern  states  as  much  as  twenty  tons  of  salt  to  the  acre  are 
often  used  for  this  purpose,  but  after  one  or  two  years  the  soil  is 
back  to  normal  again.  In  the  West  this  would  not  be  the  case,  for 
such  an  amount  of  salt  would  probably  remain  unchanged  for  many 
years.  It  has  been  said  that  the  salt-treated  areas  in  California, 
though  completely  rid  of  morning  glory,  are  not  productive  and 
remain  wet  and  boggy  during  the  spring  plowing  season,  thus  hinder- 
ing the  work  of  tillage. 

On  land  which  is  at  present  untilled  and  to  which  none  of  the 
above  objections  would  apply,  the  salt  brine  method  of  control  of 


Circular  256]  THE  control  OF  WILD  MORNING  GLORY  15 

morning  glory  recommended  by  C.  W.  Beers3  can  be  used  with 
advantage.  Along  driveways,  fence  lines,  and  ditch  banks  it  is 
especially  useful.  The  preparation  of  the  soil  must  be  thorough;  it 
should  be  spaded  or  plowed  deep  (eight  to  ten  inches)  some  distance 
beyond  the  spread  of  morning  glory,  and  finely  pulverized  in  order 
to  enable  it  to  absorb  the  solution  of  salt  quickly.  Ordinary  unrefined 
rock  salt,  dissolved  at  the  rate  of  two  pounds  to  a  gallon  of  water, 
may  be  used.  This  solution  should  be  poured  on  to  the  soil  until  it 
is  thoroughly  wet  to  a  depth  of  eight  or  ten  inches.  A  trial  of  ten 
gallons  will  determine  the  amount  necessary  to  wet  a  given  area  of 
soil.  The  amount  to  be  used  will  depend  upon  the  nature  of  the  soil 
and  the  amount  of  moisture  present  at  the  time  of  operation. 

After  the  entire  area  is  wet  to  the  desired  depth,  it  should  be 
covered  with  at  least  one  foot  of  straw,  leaves,  or  other  cheap  litter, 
and  wet  down  thoroughly.  The  straw  will  prevent  baking,  act  as 
a  mulch,  and  thus  conserve  the  moisture.  Frequent  examination 
should  be  made  from  time  to  time  to  determine  the  amount  of 
moisture  present.  Whenever  water  is  needed,  the  mulch  should  be 
thoroughly  wet  down.  Or,  rock  salt  could  be  scattered  on  the  soil  at 
the  rate  of  two  or  more  tons  per  acre  and  wet  down  thoroughly.  The 
success  of  this  method  is  dependent  upon  the  presence  of  sufficient 
moisture.    This  factor  must  not  be  overlooked. 

As  the  final  result  of  the  treatment  the  plant  is  killed  by  an  excess 
of  salt.  A  period  of  at  least  two  years  must  elapse  before  soil  so 
treated  can  be  utilized  for  crops.  If  leached  by  heavy  irrigation  or 
rains  so  that  adequate  drainage  is  afforded,  the  soil  may  perhaps  be 
recovered  eventually  for  agricultural  purposes. 

SODIUM    ARSENITE    AS    A    WEED    KILLER 

Among  the  principal  chemicals  utilized  for  the  control  of  weeds 
are  arsenic  in  the  form  of  sodium  arsenite,  iron  sulfate  for  broad 
leaved  plants  such  as  dandelions  and  mustard,  and  carbon  bisulfid. 

The  railroads  use,  during  the  late  growing  season  for  plants  on 
their  right-of-ways,  enormous  quantities  of  sodium  arsenite,  which  is 
purchased  from  the  manufacturers  in  tank-car  lots.  Arsenic  is  a 
by-product  of  the  smelting  of  ores  in  modern  metallurgy,  which  after 
recovery  as  arsenic  tri-oxide  is  made  soluble  by  treatment  with  sodium 
hydroxide  or  carbonate.  The  result  is  sodium  arsenite,  a  soluble  plant 
and  animal  poison  in  concentrated  form.  This  material  may  be  dis- 
solved as  needed  at  the  rate  of  only  one  pound  of  arsenic  to  twenty- 
five  gallons  of  water.     When   sprayed   on   vegetation,   except  most 


16  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

grasses,  and  especially  on  broad-leaved  plants,  the  solution  is 
absorbed  by  the  leaves  and  stems.  The  result  is  the  death  of  the 
plant  if  all  the  conditions  are  right.  But  just  what  these  conditions 
are  and  whether  the  maturity  of  the  plant,  the  time  of  day  when 
the  application  is  made,  the  amount  of  soil  moisture  present,  or  the 
amount  of  moisture  present  in  the  plant  itself  or  in  the  atmosphere 
are  factors  of  importance  has  so  far  not  been  fully  determined. 
Until  some  fundamental  research  work  on  the  problem  has  been  done 
and  the  factors  affecting  toxicity  of  chemicals  in  relation  to  plant 
life  are  determined,  the  use  of  chemicals  as  weed  killers  is  purely 
an  empirical  matter.  Experiments  so  far  completed  point  to  the 
importance  of  all  the  above  mentioned  factors. 

Arsenic,  in  the  form  of  sodium  arsenite,  has  been  used  by  many 
investigators  for  the  eradication  of  plant  life.  Krauss6  has  found 
this  material  very  useful  in  the  suppression  of  weed  growth  among 
pineapples  in  the  Hawaiian  Islands.  A  solution  of  one  pound  of 
arsenic  to  ten  gallons  of  water  applied  as  a  spray  between  the  rows 
proved  satisfactory  in  controlling  the  weeds.  The  soils  of  the  islands 
are  rich  in  iron,  and  due  to  the  consequent  formation  of  insoluble 
arsenic-iron  compounds  the  large  quantities  of  arsenic  annually 
applied  do  not  interfere  with  regular  crops  grown  on  the  soil. 

Arsenite  of  soda  in  the  form  of  a  spray  has  been  extensively  used 
in  Australia7  for  the  control  of  prickly  pear  and  other  undesirable 
plants.  Of  late  years,  however,  the  usage  has  been  largely  discontinued. 
In  the  rubber  plantations  of  Hawaii8  sodium  arsenite  spray  is  now 
generally  used  as  a  means  of  controlling  the  rich  plant  undergrowth 
infesting  the  plantings  of  rubber  trees.  Extensive  experiments  on 
the  control  of  morning  glory  with  arsenical  sprays  were  carried  out 
at  Berkeley,  Davis  and  Spreckels  (in  conjunction  with  the  Spreckels 
Sugar  Company)  and  at  Centerville,  Alameda  County,  in  1915,  1916 
and  1917  by  George  P.  Gray,  who  was  at  that  time  chemist  in  charge 
of  the  Insecticide  and  Fungicide  Laboratories  at  the  University  of 
California. 

Gray9  investigated  the  toxicity  or  killing  power  of  sodium  arsenite 
when  applied  either  to  the  roots  or  to  the  tops  of  vines  alone.  The 
results  obtained  were  so  completely  influenced  by  varying  condi- 
tions of  which  little  was  known  at  that  time  that  he  could  not 
predict  the  result  of  further  applications.  He  found  that  the  spray 
applied  in  a  very  dilute  solution  to  the  mature  plants  in  the  coast 
regions  actually  killed  the  roots  of  wild  morning  glory  over  the  entire 
experimental  plot  to  a  depth  of  three  to  four  feet.  A  few  of  these 
plants,  however,  revived  the  following  spring  or  summer,  although 


Circular  256]  THE  CONTROL  OF  WILD  MORNING  GLORY  17 

many  of  them  required  a  full  year  to  reach  the  surface.  As  the 
evidence  obtained  from  these  experiments  was  considered  worthy  of 
publication,  Station  Circular  No.  1689  was  printed  recommending 
this  treatment  for  morning  glory  in  the  fog-belt  of  California.  After 
the  publication  of  the  circular  further  experiments  were  carried  on 
at  various  places  in  the  state  during  the  succeeding  fall.  The  results 
of  these  investigations,  however,  do  not  warrant  the  general  use  of 
this  method  except  in  the  fog-belt.12 

Investigators  seem  to  agree  on  one  condition  only,  which  is  that 
the  plants  must  be  mature,  preferably  in  full  bloom  or  in  seed,  for 
the  spray  to  be  effective  on  the  roots.  At  present  no  recommendations 
can  be  made  as  to  the  time  or  method  of  application  of  sprays  of 
sodium  arsenite.  The  best  dosage  or  the  amount  of  arsenic  to  be 
used  in  the  spray  material  has  not  been  fully  determined  for  all 
plants.  The  various  railroads  using  this  material  for  a  general  weed 
killer  use  different  dilutions  in  different  places. 

The  dangers  associated  with  the  use  of  soluble  arsenic  are  many. 
Sodium  arsenite  is  poisonous  in  very  small  doses.  It  is  usually  very 
caustic  in  the  concentrated  form,  and  will  cause  severe  burning  if 
brought  into  contact  with  the  skin.  It  may  kill  trees  and  vines  if  it 
reaches  them  when  the  morning  glory  is  being  sprayed.  Arsenic  has 
proved  very  injurious  to  stock,  which  have  a  preference  for  eating 
plants  sprayed  with  this  poison.  Very  small  quantities  are  sufficient 
to  kill  them.  The  fumes  of  burning  arsenic  are  poisonous  to  man  or 
animal.  In  burning  plant  growth  that  has  been  sprayed  and  killed 
with  arsenic,  care  should  be  exercised  to  avoid  breathing  the  smoke. 
Arsenic  fumes  smell  like  garlic  and  are  thus  easily  detected. 

COMMERCIAL  WEED   KILLERS 

The  market  is  flooded  with  the  products  of  certain  weed  killer 
manufacturers  who  unhesitatingly  state  that  their  solutions  will 
absolutely  control  almost  any  weed,  fern,  or  grass.  It  has  been  deter- 
mined and  reported  by  the  Division  of  Chemistry  of  the  State  Depart- 
ment of  Agriculture  at  Sacramento10  that  all  samples  so  far  examined, 
with  the  exception  of  one  which  is  carbon  bisulfid,  are  simply 
solutions  of  sodium  arsenite.  Many  of  these  arsenical  herbicides 
(weed  killers),  Gray  tells  us,10  are  not  labelled  poisonous  and  may, 
for  this  reason,  endanger  the  lives  of  both  livestock  and  human 
beings.  Some  makers  state  that  their  product  is  not  poisonous  to 
land  when  applied  as  directed,  but  in  point  of  fact  a  pint  of  the 
concentrated  solution  would  sterilize  a  square  yard  of  soil  for  many 


18 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


years  and  absolutely  prevent  plant  growth.  (See  fig.  11.)  Gray10 
shows  that  the  prices  asked  for  most  of  these  herbicides  are  beyond 
reason,  and  are  proportionate  only  to  the  exorbitant  claims  made  for 
them.  Sodium  arsenite,  sold  under  that  name,  would  find  a  ready 
market  and  might  be  recommended  as  an  herbicide  for  sterilizing 
walks,  drives,  ditch  banks  and  such  places,  when  used  by  operators 
who  know  the  poisonous  nature  of  the  material  they  are  using.  Some 
companies  are  now  putting  out  sodium  arsenite  for  this  purpose. 


Fig.  11. — Sterilizing  effect  of  arsenic  on  soil  when  applied  in  heavy  doses. 
Photo  by  G.  P.  Gray. 


CARBON    BISULFID    FOR    SMALL    PATCHES 

The  treatment  of  morning  glory  with  carbon  bisulfid  has  been 
investigated  by  Thomas  Mayhew,  farm  advisor  of  Monterey  County, 
and  the  results  of  his  investigations  are  found  in  his  report  on  this 
work.  The  work  has  been  carried  on  since  the  summer  of  1919,  and 
the  investigation  has  been  thorough.  Carbon  bisulfid  is  a  volatile, 
explosive  liquid  and  ean  be  secured  in  the  markets  in  any  quantity. 
Mayhew  has  proved  that  morning  glory  may  be  eradicated  by  the  use 
of  this  chemical.  The  danger  of  fire  and  injury  from  this  compound 
should  be  carefully  guarded  against.  Mayhew  makes  the  following 
recommendations : 

The  work  should  be  done  while  the  soil  is  quite  dry  in  order  to  permit  the 
gas  formed  in  the  soil  to  spread  as  far  as  possible. 


Circular  256]  THE  CONTROL  OF  WILD  MORNING  GLORY  19 

The  liquid  is  to  be  applied  by  making  holes  three  feet  apart  each  way  over 
the  entire  surface  of  the  morning  glory  covered  patch.  These  holes  to  be  made 
with  a  bar  to  a  depth  of  eighteen  inches.  Place  four  ounces  of  carbon  bisulfid 
in^each  hole  and  fill  with  soil.  The  gas  filters  out  through  the  dry  soil  and  in 
some  manner  kills  the  weeds,  for  in  one  week  the  tops  show  the  effects,  and  in 
one  month  the  vines  are  dead. 

The  crop  yield  has  been  found  to  increase  after  using  carbon  bisulfid.  This 
result  is  apparent  the  following  year.  There  is  no  evidence  as  to  how  long  the 
ill  effects  of  the  gas  remain  in  the  soil.  This  treatment  is  especially  recom- 
mended for  small  isolated  patches  that  are  inconvenient  for  cultivation  and  for 
this  reason  would  be  neglected.  The  cost  is  almost  prohibitive  for  large  areas, 
although  it  has  proved  to  be  satisfactory  in  killing  morning  glory. 

The  use  of  carbon  bisulfid  for  eradication  of  morning  glory  in  orchards  or 
vineyards  cannot  be  recommended.  The  danger  of  killing  trees  or  vines  is  too 
great. 

In  the  preparation  of  land  for  grape  vines  in  August,  1921, 
County  Farm  Advisor  Harrison  of  Yuba  County  recommended  carbon 
bisulfid  for  eradication  of  isolated  patches  of  morning  glory  before 
planting.  Thereafter  a  certain  fruit  grower  who  was  subsoiling  forty 
acres  of  hard  pan  soil  preparatory  to  planting  vines  conceived  the 
device  of  attaching  a  container  for  carbon  bisulfid  with  an  outlet  pipe 
and  stop  cock  to  the  subsoiler,  seating  an  attendant  on  the  machine  to 
open  the  stop  cock  while  passing  through  the  morning  glory  patches 
in  order  to  allow  the  solution  to  flow  into  the  soil  directly  at  the 
bottom  of  the  furrow.  About  fifty  gallons  of  carbon  bisulfid  alto- 
gether were  used  in  this  experiment  and  the  method  proved  entirely 
satisfactory,  only  a  few  plants  appearing  the  following  spring.  These 
were  easily  hoed  out  and  completely  eradicated. 


PREVENTION 

Knowing  as  we  do  the  extent  of  the  country  infested  with  this 
weed,  it  is  advisable  to  use  all  the  precautions  possible  to  prevent  new 
infestations.  First  of  all,  the  matter  of  using  seeds  free  from  morning 
glory  is  of  vital  importance.  All  morning  glory  seeds  should  be 
removed  from  grains  used  for  seed  purposes,  especially  those  to  be 
sown  on  clean  land.  All  barnyard  manure  should  be  composted 
before  spreading,  in  case  hay  or  grain  containing  morning  glory  seeds 
is  fed  to  the  stock. 

All  small  infestations  or  patches  of  morning  glory  should  be  care- 
fully dug  out  and  the  roots  and  tap  roots  burned  or  thoroughly  dried 
out.  The  soil  should  be  piled  up  in  a  mound  one  foot  or  more  high 
over  such  treated  patches,  and  the  process  repeated  if  the  growth 


20 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


reappears.  Carbon  bisulfid  or  salt  treatment  has  proved  useful  under 
certain  conditions,  as  shown  by  this  circular.  Larger  patches  of 
the  weed  can  be  handled  by  the  "cutting"  method.  (See  fig.  12.) 
Plows  and  cultivators  when  moved  from  place  to  place  and  from 
infested  to  clean  fields  should  be  carefully  examined  and  all  traces 
of  morning  glory  removed  in  order  to  prevent  the  infestation  of  new 
fields. 


Fig.  12. — An  efficient  4 -horse  weeder  used  for  many  years  in  morning  glory  control. 
This  three-blade  type  is  best  adapted  to  rough  land. 


Circular  256]  THE  control  of  wild  morning  glory  21 


SUMMARY 

1.  Morning  glory  or  bindweed  is  called  botanically  Convolvulus 
arvensis  Linnaeus.     It  is  a  perennial  of  great  economic  importance. 

2.  It  is  found  throughout  California  and  is  well  distributed  over 
the  United  States. 

3.  The  persistent  growth  of  this  plant  after  repeated  cuttings  is 
due  to  the  large  amount  of  plant  food  stored  in  the  roots.  This  food 
must  be  exhausted  in  order  to  kill  the  plant. 

4.  Cultivation  (cutting  below  the  surface),  if  thorough  and  fre- 
quently enough  employed  during  one  growing  season,  will  kill  the 
plant  in  one  year.  The  interval  between  cuttings  should  generally 
not  be  greater  than  five  days.    Never  allow  green  leaves  to  appear! 

5.  Alfalfa  may  kill  out  morning  glory  in  two  to  three  years.  A 
good  stand  is  necessary.  Alfalfa  yields  profitable  crops  at  the  same 
time. 

6.  Covering  morning  glory  with  straw  or  other  dead  material 
will  not  check  its  growth. 

7.  Hogs  may  in  California,  in  certain  instances,  kill  out  morning 
glory  by  eating  its  roots.  This  method  is  used  extensively  in  the 
eastern  states.  Sheep  aid  in  the  work  by  grazing  on  the  green  parts 
of  the  plant. 

8.  Salt  brine  will  kill  morning  glory.  It  is  recommended  for  soil 
not  used  for  crop  purposes. 

9.  Sodium  arsenite  is  toxic  to  plants.  It  is  used  in  many  places 
as  an  herbicide.  Kecommendation  of  its  general  use  on  morning 
glory  is  not  justified  by  the  investigations  made. 

10.  Commercial  weed-killers,  largely  solutions  of  sodium  arsenite, 
are  too  expensive  and  cannot  be  recommended  for  the  reason  that  no 
one  knows  just  when  to  apply  them. 

11.  For  small  patches  of  morning  glory  carbon  bisulfid  is  very 
satisfactory. 

12.  The  eradication  of  small  colonies  at  the  beginning  will  save  a 
great  deal  of  expense  later  on. 


22  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


LITERATURE    CITED 

i  Sixth  Annual  Report  of  the  Spreckels  Sugar  Company  Agricultural  Experiment 
Station. 

2  Cox,  H.  R.     1909.     U.  S.  D.  A.,  Farmers'  Bull.  368.     The  Eradication  of  Bind- 
weed or  Wild  Morning  Glory. 

s  Beers,    C.    W.,    Hort.    Comm.    Santa    Barbara    County    California.      Practical 
Methods  of  Exterminating  Noxious  Weeds. 

4BIOLETTJ,  F.  T.     1911.     Cir.  69,  U.  C.  Agr.  Exp.  Station.     The  Extermination 
of  Wild  Morning  Glory. 

5  Hendry,  Geo.  W.     1920.     Pacific  Rural  Press,  vol.   100,  p.  10,  July  3,   1920. 
The  Control  of  Mo  ruing  Glory. 

e  Westgate,   J.   M.      1915.     Press   Bull.    No.    48,  Hawaii   Agr.    Exper.   Station. 
Suppression  of  Weeds  among  Pineapples  by  Arsenite  of  Soda  Spray. 

7  Agricultural  Gazette,  N.  S.  W.,  9  (1898),  p.  984. 

s  Wilcox,  E.  V.     Press  Bull.   30,  Hawaii  Agr.   Exper.   Station.     Killing  Weeds 
with  Arsenite  of  Soda. 

9  Gray,  G.  P.     1917.     California  Agr.  Exp.  Sta.  Cir.  168.     Spraying  for  Control 
of  Wild  Morning-glory  within  the  Fog  Belt. 

io  Gray,  G.  P.     1921.     Herbicides,  Monthly  Bull,   of  Cal.    State  Dept.   of  Agr. 
Weeds  of  California  and  Methods  of  Control. 

ii  Hillman,  F.  H.     1897.    Nevada  Agr.  Exper.  Sta.,  Bull.  38,  Nevada  Weeds,  III. 
Nevada  and  other  Weed  Seeds. 

12  Gray,   G.    P.      1919.      Report    of   Progress    Tests   of   Chemical   Means    for   the 

Control  of  Weeds.     Univ.  Calif.  Publ.  Agr.  Sci.,  vol.  4,  no.  2,  pp.  67-97. 

13  Jepson,  W.  L.     Flora  of  Middle  Western  California. 


STATION  PUBLICATIONS  AVAILABLE  FOE  FKEE  DISTRIBUTION 


BULLETINS 


No. 

253.  Irrigation  and  Soil  Conditions  in  the 
Sierra  Nevada  Foothills,  California. 

261.  Melaxuma    of    the    Walnut,     "Juglans 

regia." 

262.  Citrus   Diseases   of   Florida    and    Cuba 

Compared  with  those  of  California. 

263.  Size  Grades  for  Ripe  Olives. 

268.   Growing  and  Grafting  Olive  Seedlings. 

270.  A  Comparison  of  Annual  Cropping,  Bi- 
ennial Cropping,  and  Green  Manures 
on  the  Yield  of  Wheat. 

273.  Preliminary  Report  on  Kearney  Vine- 
yard  Experimental  Drain. 

275.  The  Cultivation  of  Belladonna  in  Cali- 

fornia. 

276.  The    Pomegranate. 

278.  Grain   Sorghums. 

279.  Irrigation  of  Rice  in  California. 

280.  Irrigation  of  Alfalfa  in  the  Sacramento 

Valley. 
283.   The  Olive  Insects  of  California. 

285.  The  Milk  Goat  in  California. 

286.  Commercial    Fertilizers. 

287.  Vinegar  from  Waste  Fruits. 
294.   Bean    Culture   in   California. 

297.  The  Almond  in   California. 

298.  Seedless  Raisin  Grapes. 

299.  The  Use  of  Lumber  on  California  Farms. 
304.   A  study   on   the  Effects  of   Freezes  on 

Citrus    in    California. 

308.  I.  Fumigation  with  Liquid  Hydrocyanic 
Acid.  II.  Physical  and  Chemical  Prop- 
erties of  Liquid  Hydrocyanic  Acid. 

310.    Plum  Pollination. 

312.  Mariout   Barley. 

313.  Pruning  Young   Deciduous  Fruit  Trees. 

316.  The   Kaki   or   Oriental   Persimmon. 

317.  Selections   of   Stocks   in   Citrus   Propa- 

gation. 


No. 
319. 
321. 
324. 

325. 


328. 
330. 
331. 
332. 
334. 

335. 

336. 

337. 
339. 

340. 

341. 

342. 
343. 
344. 

345. 

346. 
347. 

348. 
352. 

353. 
354. 

355. 


Caprifigs  and  Caprification. 

Commercial  Production  of  Grape  Syrup. 

Storage  of  Perishable  Fruit  at  Freezing 
Temperatures. 

Rice  Irrigation  Measurements  and  Ex- 
periments in  Sacramento  Valley, 
1914-1919. 

Prune  Growing  in  California. 

Dehydration  of  Fruits. 

Phylloxera-Resistant   Stocks. 

Walnut  Culture  in  California. 

Preliminary  Volume  Tables  for  Second- 
Growth  Redwoods. 

Cocoanut  Meal  as  a  Feed  for  Dairy 
Cows  and  Other  Livestock. 

The  Preparation  of  Nicotine  Dust  as 
an  Insecticide. 

Some  Factors  of  Dehydrater  Efficiency. 

The  Relative  Cost  of  Making  Logs  from 
Small    and    Large   Timber. 

Control  of  the  Pocket  Gopher  in  Cali- 
fornia. 

Studies  on  Irrigation  of  Citrus  Groves. 

Hog  Feeding  Experiments. 

Cheese  Pests  and  Their  Control. 

Cold  Storage  as  an  Aid  to  the  Market- 
ing of  Plums. 

Fertilizer  Experiments  with  Citrus 
Trees. 

Almond    Pollination. 

The  Control  of  Red  Spiders  in  Decidu- 
ous Orchards. 

Pruning  Young:  Olive   Trees. 

Further  Experiments  in  Plum  Pollina- 
tion. 

Bovine  Infectious  Abortion. 

Results  of  Rice  Experiments  in   1922. 

The  Peach  Twig  Borer. 


No. 

70.  Observations  on  the  Status  of  Corn 
Growing  in  California. 

82.  The  Common  Ground  Squirrel  of  Cali- 
fornia. 

87.  Alfalfa. 

110.  Green  Manuring  in  California. 

111.  The  Use  of  Lime  and  Gypsum  on  Cali- 

fornia Soils. 
113.   Correspondence  Courses  in  Agriculture. 

126.  Spraying  for  the  Grape  Leaf  Hopper, 
136.  Melilotus    indira    as    a    Green-Manure 

Crop  for  California. 

127.  House  Fumigation. 

144.   Oidium  or  Powdery  Mildew  of  the  Vine. 
148.    "Lungworms." 

151.  Feeding  and  Management  of  Hogs. 

152.  Some    Observations  on  the  Bulk    Hand- 

ling of  Grain  in   California. 
155.   Bovine  Tuberculosis. 
157.   Control  of  the  Pear  Scab. 

159.  Agriculture   in   the   Imperial   Valley. 

160.  Lettuce  Growing  in  California. 

161.  Potatoes  in   California. 

164.  Small  Fruit   Culture  in   California. 

165.  Fundamentals    of    Sugar    Beet    Culture 

under  California  Conditions, 
lfifi.   The  County  Farm  Bureau. 
167.   Feeding  Stuffs  of  Minor  Importance. 

169.  The    1918   Grain   Crop. 

170.  Fertilizing  California  Soils  for  the  1918 

Crop. 


CIRCULARS 

No. 

172. 
173. 


174. 
175. 

178. 
179. 

181. 

182. 

183. 
184. 
188. 
189. 
190. 
193. 
198. 
199. 
201. 
202. 

203. 
205. 
206. 
208. 

209. 
210. 


Wheat  Culture. 

The    Construction    of    the    Wood-Hoop 

Silo. 
Farm   Drainage  Methods. 
Progress  Report  on  the  Marketing  and 

Distribution  of  Milk. 
The  Packing  of  Apples  in  California. 
Factors    of    Importance    in    Producing 

Milk  of  Low  Bacterial  Count. 
Control     of     the     California      Ground 

Squirrel. 
Extending  the  Area  of  Irrigated  Wheat 

in   California  for  1918. 
Infectious  Abortion  in  Cows. 
A  Flock  of  Sheep  on  the  Farm. 
Lambing  Sheds. 
Winter  Forage  Crops. 
Agriculture  Clubs   in   California. 
A  Study  of  Farm  Labor  in  California. 
Syrup  from   Sweet  Sorghum. 
Onion  Growing  in  California. 
Helpful  Hints  to  Hog  Raisers. 
County    Organizations   for   Rural    Fire 

Control. 
Peat  as  a  Manure  Substitute. 
Blackleg. 
Jack  Cheese. 
Summary  of  the  Annual  Reports  of  the 

Farm   Advisors  of  California. 
The  Function  of  the  Farm  Bureau. 
Suggestions  to  the  Settler  in  California. 


CIRCULARS — Continued 


No. 
212. 
214. 

215. 
217. 

218. 

219. 
224. 


225. 
228. 
230. 

232. 

233. 
234. 

235. 

236. 

237. 


No. 
Salvaging  Rain-Damaged  Prunes.  238. 

Seed  Treatment  for  the  Prevention  of  239. 

Cereal  Smuts. 
Feeding  Dairy  Cows  in  California.  240. 

Methods   for   Marketing   Vegetables   in 

California.  241. 

Advanced    Registry    Testing    of    Dairy 

Cows.  242. 

The  Present   Status  of  Alkali.  244. 

Control    of    the    Brown    Apricot    Scale  245. 

and  the  Italian  Pear  Scale  on  Decid-  246. 

uous  Fruit  Trees. 
Propagation  of  Vines.  247. 

Vineyard   Irrigation  in   Arid  Climates.  248. 

Testing  Milk,    Cream,    and    Skim   Milk 

for  Butterfat.  249. 

Harvesting    and    Handling    California  250. 

Cherries  for  Eastern  Shipment. 
Artificial  Incubation.  251. 

Winter  Injury  to  Young  Walnut  Trees 

during  1921-22. 
Soil  Analysis  and  Soil  and  Plant  Inter-  252. 

relations.  253. 

The  Common  Hawks  and  Owls  of  Cali-  254. 

fornia   from    the     Standpoint   of  the 

Rancher.  255. 

Directions  for  the  Tanning  and  Dress- 
ing of  Furs.  256. 


The  Apricot  in  California. 

Harvesting  and  Handling  Apricots  and 
Plums  for  Eastern  Shipment. 

Harvesting  and  Handling  Pears  for 
Eastern   Shipment. 

Harvesting  and  Handling  Peaches  for 
Eastern   Shipment. 

Poultry  Feeding. 

Central  Wire  Bracing  for  Fruit  Trees. 

Vine  Pruning  Systems. 

Desirable  Qualities  of  California  Bar- 
ley for  Export. 

Colonization  and  Rural  Development. 

Some  Common  Errors  in  Vine  Pruning 
and  Their  Remedies. 

Replacing  Missing  Vines. 

Measurement  of  Irrigation  Water  on 
the   Farm. 

Recommendations  Concerning  the  Com- 
mon Diseases  and  Parasites  of 
Poultry    in    California. 

Supports  for  Vines. 

Vineyard   Plans. 

The  Use  of  Artificial  Light  to  Increase 
Winter  Egg  Production. 

Leguminous  Plants  as  Organic  Fertil- 
izer in  California  Agriculture. 

The  Control  of  Wild  Morning  Glory. 


